VGB POWERTECH Issue 1/2 (2020)

Sector Coupling – buzzword or future of the energy supply VGB PowerTech 1/2 l 2020
can be achieved. Then, I would ask what
point of view should I take? From the electricity,
or mobility, or industrial view point?
The concern for risk in sharing internal information
can be a high barrier for possible
partners to implement Sector Coupling. It is
a special – non technical – hurdle which
varies with the mentality of each partner.
What are these hurdles and the related questions
to be answered? What is my business
model? What is my benefit? Why am I sharing
my internal key figures to an external
organization? Could my production or my
products be influenced by Sector Coupling?
It is my impression that the process of partnering
could be compared with a marriage.
A couple will never be happy if a spouse is
thinking only about personal own benefit.
For a long lasting partnership, things are developed
jointly through thinking and developing
activities jointly. It is meeting the
common goals for the benefits of the family.
Even in the most developed form of Sector
Coupling – combined heat and power –
some challenging questions sometimes
arise. “If you would use my waste heat can
my production process be affected? Can a
failure in waste heat utilization have a negative
impact on my production?
The only way to solve these kinds of problems
is open communication and problem
solving to develop the necessary solutions.
Problems include reducing CAPEX and
OPEX but also improving or maintaining
the quality of the products in a manufacturing
process.
Hydrogen, grids and
regulatory frame work
Another piece of the puzzle is hydrogen. In
the future, hydrogen will play a more
prominent role in Sector Coupling. Already,
there is great interest in hydrogen
and there are many R&D (Research & Development)
projects.
Hydrogen is not a primary energy. It has to
be generated in future by renewables but it
is currently mostly made by steam reforming.
Sector Coupling without hydrogen is
not possible. Flexibility and mass storage
need hydrogen. As shown in F i g u r e 6 ,
hydrogen could be used directly as a fuel or
a feedstock for making synthetic fuels.
Today, hydrogen is produced mainly from
natural gas and coal via steam reforming. It
is so called grey hydrogen. If CO 2 formed
during steam reforming is separated and sequestrated,
hydrogen “changes color” and
becomes blue hydrogen. Surplus electricity
generated by renewables can be transferred
via hydrogen (green hydrogen) by electrolysis.
Electricity can be regenerated later on
again from combustion of hydrogen. It is
important to increase the hydrogen generation
independently of the source, to gather
experience with the infrastructure and use
of hydrogen. Economics is currently the biggest
hurdle for green hydrogen, instead of
grey hydrogen; but an energy turnaround
and as well a Sector Coupling are enabled
by the use of hydrogen. Related technologies
for energy turnaround and Sector Coupling
depend on hydrogen as energy carrier
and chemical feedstock.
For the German market, plants are needed
that can flexibly generate electricity or hydrogen.
Depending on the market conditions,
the plants can either produce hydrogen
or electricity to maximize profitability.
EEG must honor not the feed in of renewable
electricity but the consumption of renewable
electricity. Then it is possible to
decide to sell or to store electricity. This
would make renewable hydrogen more attractive.
In the context of Sector Coupling, all products
and by-products should be used in the
future. A key to improving the business
model for production of hydrogen by electrolysis
is to profitably turn oxygen into a
co-product of hydrogen.
Another challenge in using large scale electrolysis
to product green hydrogen is the
use of a large amount of water. When talking
about electrolysis in huge dimensions
not only the electricity consumption has
to be considered but also the consumption
of treated water. The water consumption
to bridge a two week dark doldrum could
be like the drinking water consumption
of a 200.000 inhabitant city in a year. So
this restriction is limiting the hydrogen
generation in very sunny regions where
sufficient amount of water is typically not
available.
Today, hydrogen is used by industry for refining
petroleum, treating metals, producing
fertilizer, processing foods, cooling electric
generators, or driving fuel cells. In the
steel industry, a transformation process will
happen when hydrogen replaces coke to reduce
iron. However, this form of Sector
Coupling will be determined by the new
world price of steel and the resulting economics.
Hydrogen could play a strong role in energy
storage and as grid stabilizer in the future.
Surplus electricity from renewables
could be used to generate hydrogen via
electrolysis. Hydrogen could be transported
in the natural gas grid and converted to
electricity at a later date. It is also energy
for fuel cells. Thus, the sector power can be
coupled with the sector gas.
Open Grid Europe (OGE) and Amprion, as
transmission system operators for gas and
electricity, respectively, are discussing a
large scale power-to-gas pilot project “Hybridge”.
Power-to-gas technology plays a
major role in the transformation of our energy
system. It allows green electricity to
be converted into hydrogen which can be
used in other sectors. It also allows using
the gas infrastructure to store renewable
energy. The goal for the pilot plant is to be
able to convert up to 100 MW of electrical
energy into hydrogen by 2023. An electrolyzer
will be installed near one of Amprion’s
substations and connected to Amprion’s
electricity grid. OGE plans to convert
parts of its existing gas network for the exclusive
transport of pure hydrogen. Companies
located near the new hydrogen
pipeline can use the green hydrogen. In the
further course of the project, there is provision
for hydrogen filling stations for motor
vehicles or trains in the mobility sector. In
addition, natural gas storage facilities will
be converted for storing hydrogen. Thus,
the demand for hydrogen can be decoupled
from the supply of renewable energy.
Hydrogen can be supplied from the storage
facilities on demand. In this way, a reliable
supply of green hydrogen can be efficiently
realized.
Sector Coupling at the system level involves
transformation between two regulated
areas – the electricity transmission
network and the gas transmission network.
It is planned for the transmission system
operators to be responsible for the planning,
construction and operation of the
sector transformer, i.e., the power-to-gas
plant. This is intended to be financed
through network charges.
A key approach for solving the problem of
increasing quantities of electricity from
wind and solar that do not always find consumers
is to direct this electricity to other
sectors – where large amounts of energy
are required. This is technically possible by
coupling the existing infrastructures of the
German electricity and gas system with
each other. Power-to-gas systems act as a
bridge between the individual systems.
Similarly, hydrogen can be a feedstock for
producing synthetic methane.
Today, the transformation and transport of
energy takes place within each system separately.
For example, in the electricity value
chain, power plants feed electricity into
the grid. This electricity is then transmitted
via transmission lines, passed on to other
voltage levels via current transformers and
transported on from there to the end customers.
Gas transport works in a similar
way – from the transport network via the
regional network to the distribution network.
The power-to-gas approach provides
an option to transport energy between sectors.
Here, electricity is converted into hydrogen
in the power-to-gas system, fed into
the gas system and transported on to the
respective point of consumption. There are
three criteria crucial for Sector Coupling to
achieve maximum economic benefits and
maximum sustainability:
––
Size: The power-to-gas plants must be
integrated into the electricity and gas
system in a suitable dimension and at
large scale
––
Location: The systems must be installed
at suitable contact points between the
electricity and gas transport networks
––
Timing: It must be possible to coordi-
40